You need a plan with a scale to answer that question.
You'll be able to have a good estimation here with the small-sized plans at the bottom of the web page. The man with his tricorn and vertical stick serves as scale (1m, 2m, 3m). And the waterline is shown.
Or buy the book. 🙂
Writing a book or fiction thread ?

in fact, the game takes place during the battle of Trafalgar, somewhere between 1680 and 1820. No lies !
Well... 'French royalists', that is French inhabitants of Haiti who were against the French Revolution were mostly white pro-slavery (aristocrat) planters fighting against the French Revolution and joining GB/Spain notably because they were against the abolition of slavery and wanted more autonomy/power over the homeland. See for example Mauduit. They lost.
... while the black slaves/free ppl of Haiti fought for the independence against the French Revolution then against Napoleon and won.
Both factions (not to mention Spain and GB) fought against the French Revolution but for quite opposite reasons.

Indeed, I guess NA timeframe was made to have a collection of homogeneous ships in game ('same' armament, no steamboat...).
The date of construction of the Hellas (1826) is very close to the limit of NA time frame (1820). Some mod even spoke of 1820 +/- 5 years.
The Hellas doesn't seem over-powered compared to the others ships in NA. Correct me if I'm wrong.
+ it'd add a new nation of ships in game.
PS : on a final note, a fun nod about the 'Hellas' for our French-speaking ones :

well... my point was actually to make NA more historical, not less (by adding more non-historical flags).
And the more non-historical flag implemented in game for this timeframe, that should be definitely deleted, is the white flag of the surrender system and of the Neutral.
And the French warships should be given back the only naval ensign they used during 115 years out of the 140 years of NA time frame : the white monarchic ensign.

...that wasn't even the case for La Belle Poule, La Renommée, L'Hermione, Le Requin or L'Unité that never carried any caronade anywhere IRL :
Le Requin and La Renommée were broken up before the invention of carronades.
L'Hermione had been exclusively sailed by the French and was wrecked before France used caronades.
La Belle Poule had been sailed by the French before France used caronades and it seems British did not put caronades on her after her capture
Only French L'Unité got caronades but that was only after her capture and her renaming/refitting as HMS Surprise.
(edit)
Likewise, HMS Cerberus (burnt before the invention of caro) never carried caronades.

La Belle Poule, La Renommée, L'Hermione, Le Requin, L'Unité never carried carronades, according to threedecks.org and to the fact that French navy introduced caronades only in 1795 (1780 for the RN ?).
About the other ships, I do not know.

It may indeed be interested to listen to the main users of the PvE server to know what they think.
Think of the PvE server as if it emulates the PvP server, not as if PvE-ers considered bots as farming. Thus, aren't there PvPers on the War Server who like patrolling in the OW hoping for lonely preys and 1 vs 1 ? The same goes with PvE-ers on the PvE server. The way to create content on the PvE server and the way make any AI is to emulate life. Would PvP-ers who like 1vs1 be satisfied if there were only missions to get 1vs1 ?
What can you find on the PvP server ?
human players attacking you in your trader
lonely prey you can attack in the OW
etc.
Thus, what should you find on the PvE server ? The same things but designed for PvE :
bots attacking you in your trader
lonely bots you can attack in the OW
etc
Talking here about immersion in PvE as content.
IMO

Why ?
Didn't you like your RL trip on L'Hermione, @Marquis de la Fayette ? The ship was too small for you ? 🙂
These missions may encourage ppl to sail small ships, that are far too underused up to now, to carry those passengers and letters and also patrol in OW to catch them, making small ships more useful.
The more there will be OW fights between small ships (and diversity in NA), the better.
btw, being forced to use a 4th-Rate or a Sol to carry a passenger inside the Caribbean seems weird.